Question

The decreasing order of reactivity towards electrophilic addition (e.g. addition of `HX,X_(2),` etc.) of the following is `:`
`I. CH-= CH`
`II. CH_(2)=CH_(2)`
`III.` `H_(2)C=CH-Cl`
`IV`
A. `(II)gt(I)gt(III)gt(IV)`
B. `(I)gt(II)gt(III)gt(IV)`
C. `(IV)gt(III)gt(I)gt(II)`
D. `(IV)gt(III)gt(II)gt(I)`

Answer 1

Correct Answer - a
The order of electrophilic addition `(EA)` is `:` alkene `gt` alkyne. But if alkene has `EWG`, reactivity of alkene is less than that of alkyne.
Due to `EWG`, `vec(e)` dencity at `(C=C)` or nucleophilicity decreases, so addition of electrophile to `(C=C)` is slow.
So the decreasing order of `EA` is `:`
`(II)(`alkene `)gt(I)(`alkyne `)gt(III)(`alkene with one `EWG)gt(IV)(`alkene with two `EWG)`